<DOCTYPE html>
    <html>
        <body>
            <p>点击这个按钮，获得基于时间的问候。</p>
            <button onclick="myFunction()">点击这里</button>
            <p id="demo"></p>
            <script>
            function myFunction()
            {
                var x=""
                var time=new Date().getHours();
                if (time<10)
                {
                    x="good mornig"
                }
                else if (time<20)
                {
                    x="good day";
                }
                else
                {
                    x="good evening";
                }
                document.getElementById("demo").innerHTML=x;
            }
            </script>
        </body>
    </html>